Lighting-fitting



W. .l. PULLOCK. LIGHTING FITTING.

APPLXCATION FILED mac. so, 1919.

1 m m w M nears WILLIAM JOHN PULLOCK, 01E GERMIST ON, TRANSVAAL, SOUTH AFRICA.

LIGHTING-FITTING.

rename.

Application filed December 30, 1919. Serial N0. 348,421.

To all whom it mag/concern:

Be it known that l, .Viinnmar JOHN Pun more a British subject, residing at Germt ston, Transvaal Province of the Union of South Africa, have invented certain new and useful Improvements in LightingFittings, of which the following is a specification.

The present invention relates to lamp supports comprising a lamp carrying arm which is universally jointed and extensible, whereby the lamp can be moved universally within the extremelimits of movement of the fitting.

The object of the invention is to provide such a fitting in which the weight of the arm in its various positions is to a large.

extent counterbalanced by a counterweight, the variationsin regard to the sustaining counterweight forceof the effective falling weight of the arm due to the various angular positions or extensions of the latter being made up by frictional resistance between the moving parts, which resistance may be provided by a special frictional device.

The invention is illustrated in the accompanying drawing in which Figure I is an elevation of a single lamp fixture. Fig. 11' shows a cluster carrying several lamps arranged for independent movement.

Fig. HT is an enlarged detail view of the friction device shown in Figs. I and II and Fig. IV is an end view of Fig. HT.

1 indicates a fixture adapted to be secured to a ceiling or other suitable part of a building. On said fixture 1 an arm 2 is mounted to rotate, the arm extending transversely from its axis of rotation. In Fig. I the arm is shown as formed with a hub 3 journaled on a cylindrical downward extension 4: of the fixture 1 and supported by a flange 5 on said extension 1.

In the construction shown in Fig. II each arm 2. is formed with a journal 6 which is mounted in a downwardly extending part 7 of the fixture 1, and is carried on supporting flange 8.

On the arm 2 at 9 an extensible rod 10 is pivoted to swing in a vertical plane. Said rod consists of several sections indicated by 10310", 10, which are movable longitudinally with respect to one another with slight frictional resistance sufiicient to hold them relatively fixed when variously extended. Provision is made for frictionally holding said rod at various angular positions with regard to the arm 2. In the examples there is shown for this purpose an are 11 rigidly connected to the arm 2, a casing 12 fixed to the rod section 10 and friction shoes13 mounted in said casing and pressed onto the edges of the are 11 by springs 14. Said springs bear against screw plugs 15 by which their pressure may be regulated.

The lamp 16 is mounted on the outer end of the rod 10. Current is supplied by a flexible cord 17 which passes through an axial hole 18 in the part 3 or 6, as the case may be. Thence it is carried around the pulley 19 of a counter weight 20, to a pulley 21 on the inner end of the arm 2. The cord 17 is so arranged that it is effective in supporting the weight of the arm 10 and lamp 16, and for this purpose the cord is carried from the pulley 21 to another pulley 22 arranged on the arm 2 at a distance from the pivot 9. Thence it extends to a suitable point of the rod 10 by a section 17 which is tensioned by the weight of the rod and lamp. Said point on the rod 10 may be the pulley 23 mounted on the arm section 10 whence the cordis led along the arm, giving a neat appearance.

It will be seen that the lamp has three movements, viz :the extension movement of the rod 10; the vertical swinging movement of the rodlO; and the rotative movement of the arm 2 and its attached parts about the axis of rotation. The lamp can thus be placed in any position within a space defined by'the limits of extension of the rod 10 and in the group construction shown in Fig. 11 the lamps can either be separately extended Specification of Letters Patent. Patented NOV. 29, 1921.

or brought nearer together to concentrate the light at a particular point. Any up or down' swinging movement of the arm, or any extension movement of the same,1n other words any movement havlng a vertical component,is communicated .to the counterweight 20, which moves in the opposite sense to the arm and thus to a large extent counterbalances the same in all positions of the latter. The relatively small deficiency or excess of the counterbalancing force of the weight 20 is supplied by the friction of the device 11, 12, 13 and the friction between the arm sections 10 10, 10. Such frictional resistance can accordingly be small so that the lamp can readily be moved without imposing undue stresses on the arm structure.

I claim.

1. A lamp fitting comprising an extensible rod adapted to carry a lamp at its end, a support to which said rod is pivoted to swing in a vertical plane, frictional means for adjustably positioning the rod, a flexible cord suspended from a fixed part and providing a bight, a weighted pulley adapted to compensate part of the Weight of said extensible rod in said bight, said cord thereafter extending from a point on the support remote from the pivot and being fixed to the rod at a point also remote from the pivot.

2. A lampfitting comprising a horizontally extending arm, a rod'eomposed of a first section and other sections extensible therefrom, the first section being pivoted to said arm near to the inner end of the same, to swing in a vertical plane, frictional means restraining movement of the rod relatively to the arm, a pulley at the inner end of the arm, a pulley at the outer end of the arm, and a pulley on the outer end of the first rod section, a flexible cord formed with a bight one run of which is suspended from a fixed point, the other run extending to the inner pulley in the arm, and a Weighted pulley suspended in said bight, the cord beingfurther passed over the pulley at the outer end of the arm and the pulley on the first rod section and the end of the cord being fixed to the last extensible'arm section.

3. A lamp fitting comprising a supporting bracket, a horizontally extending arm pivoted thereto to rotate about a vertical axis, an extensible rod pivoted to the arm to swing in a vertical plane, frictional restraining means between the arm and the rod, a flexible cord suspended from the axis of rotation of the arm and forming a bight, a weighted pulley suspended in said bight, said cord being thereafter extended between the arm and the rod to be tensioned by the weight of the rod.

In testimony whereof I aflix my signature.

XVILLIAM JOHN PULLOCK. 

